Mazda 3 Sedan 2020 Owner's Manual page 45

CAUTION
When installing a head restraint,
make sure that it is installed correctly
with the front of the head restraint
facing forward. If the head restraint is
installed incorrectly, it could detach
from the seat during a collision and
result in injury.
The head restraints on each of the
front and rear seats are specialized to
each seat. Do not switch around the
head restraint positions. If a head
restraint is not installed to its correct
seat position, the effectiveness of the
head restraint during a collision will
be compromised which could cause
injury.
Essential Safety Equipment
Seats
2-19